Cutting device for sewing machines

ABSTRACT

A cutting device for sewing machines in particular for the cutting of sewn tapes, lace, or the like, is disclosed and comprises a knife arranged with respect to the direction of feed behind the presser foot of the sewing machine. The knife cooperates with a stationary anvil to achieve a cutting strike perpendicular to the surface of the sewn material and has drive means for the actuating of the cutting device. At least one of the bearing means which assures the cutting strike of the knife is angularly settable and adjustably by a setting means in a plane perpendicular to the movement of the cutting stroke.

United States Patent 1191 [111 3,848,554 Kropf Nov. 19, 1974 CUTTING DEVICE FOR SEWING l,l16,70l 11/1914 Hilton 112/122 MACHINES FOREIGN PATENTS OR APPLICATIONS Inventor: Manfred op ac aut 27,790 11 /1903 Switzerland 112/122 Germany [73] Assignee: Triumph International Primary Hampton Hunter Akfiengesenschaft Munchen, Attorney, Agent, or FzrmToren, McGeady and Germany Stanger PP 4 386,546 A cutting device for sewing machines in particular for the cutting of sewn tapes, lace, or the like, is disclosed [30] Foreign Application Priority Data and comprises a knife arranged with respect to the di- Au 9 1972 German 2239148 rection of feed behind the presser foot of the sewing y machine. The knife co-operates with a stationary anvil to achieve a cutting strike perpendicular to the surface 8 112,124 1 12/ i d of the sewn material and has drive means for the actu- 58] HFie'ld 130 125 ating of the cutting device. At least one of the bearing a means which assures the cutting strike of the knife is angularly settable and adjustably by a setting means in [56] References Cited a plane perpendicular to the movement of the cutting st k UNITED STATES PATENTS m e 259,840 6/1882 Fowler 112/129 7 Clams 1 Draw'ng F'gure CUTTING DEVICE FOR SEWING MACHINES BACKGROUND OF THE INVENTION The invention relates to a cutting device on sewing machines, particularly for the cutting of tapes, lace, or the like after they have been sewn to a piece of fabric.

Upon sewing tapes or lace to garment edges, as well as upon reinforcing of seams through the sewing on of a seam tape, it becomes necessary to sever the sewedon tape-like fabric from its supply after completion of the sewing-on process. For the purpose of rendering the finishing process more efficient, it is customary to arrange at the sewing machine work output end a cutting device whose blade strike is actuated by the operator as required, which can however, in the case of massproduced items, be actuated also automatically by control means scanning the work. With the cutting devices hitherto used in the art, the cutting line extends as a rule perpendicular to the direction of feed and therefore also perpendicular to the edge of the tape-like article to be sewn on.

It is frequently necessary that the cutting line on the tape-like work must, in conformity with the shape of the edge of the carrier work, run obliquely to the edge of the tape or lace. In such instances, it is necessary to change in each given case the size of the cutting line angle in conformity with the longitudinal direction of the tape. While it does not present any problem to adjust the known cutting devices in such a way that the cutting line constitute a certain angle with respect to the feed line, it would be necessary to use with such cutting devices a separate device for each angle size, or else to convert or change the setting of the tape cutting device within the machine through cumbersome measures. In practice, therefore, in the event of an oblique cutting edge, the use of a tape-cutting device attached to the sewing machine was dispensed with and the tape manually cut by the operator.

It is an object of the invention to obviate this drawback and to make it thereby possible to provide for operation of the tape-cutting process in any angular position of the cutting line with respect to the longitudinal direction of the tape by providing a cutting device adjoined to the sewing machine and, if indicated, actuated by means of a servo arrangement, and which replaces the hitherto customary manual cutting process.

The invention is based on the engineering objective of enabling the blade holder of a cutting device affixed to a sewing machine to perform, in addition to its customary cutting stroke movement substantially perpendicular to the sewing machine guide plate, another adjustable angular movement in a plane perpendicular to the movement of the cutting stroke where both degrees of freedom of movement are independent of one another.

For the purpose of obtaining the aforementioned object, the invention is based on a known tape-cutting device (U.S. Pat. No. 2,681,019) where the cutting blade strikes a stationary anvil. By comparison with the devices operating with a movable and stationary cutting blade, this design offers the advantage that the angular displacement of the cutting knife has to be performed for one knife only.

In connection with Feston sewing machines there has already become known a cloth-cutting device (German Pat. No. 421,944), in which the cutting line is adjusted through angular adjustment of the two cutting knives in accordance with the requirements of the Feston seam. With this known arrangement, the direction of the cutting line is positively adjusted to the type of the Feston work by means of a special gear. Apart from the comparatively complicated design of the known Feston cutting device, it is not possible to achieve with this arrangement an adjustment of the cutting position that would be independent of the strike of the knife.

The principle as regards the desired engineering objective described above resides, in accordance with the invention, in that the bearing means provided with the cutting blade and assuring the strike of the knife are angularly settable and adjustable by a special manual setting means in a plane perpendicular to the cutting stroke motion. Preferably, it suffices if one of the two bearing means is settable and adjustable in the aforementioned manner, provided its co-operation with the other bearing means is independent of the angular, oblique position.

In the case of the objectives achieved in accordance with the invention the oblique position of the cut can be adjusted at any time in any way desired through a change in setting of the special manual setting means. In the process, this special setting means can be manually adjusted by the operator as required. It is, however, also readily possible to adjust the special manual setting means automatically by means of a scanning device effective on the sewing material to conform to the respective shape of the edge of the item to be sewn.

It is advantageous if the device in accordance with the invention is arranged in such a way on the sewing machine that the axis around which the angular adjustment is brought about is arranged parallel to the axis of the presser-foot bar and is situated in the direction of feed. It is even preferred that the means for the angular swing and for the cutting stroke movement of the knife are arranged coaxially to the presser-foot bar. This design permits the comparatively simple subsequent installation of the device in accordance with the invention in an existing sewing machine in view of the fact that it is generally adequate if the bearing bushing of the presser-foot bar in the lower wall of the sewing machine head is removed and the device in accordance with the invention is substituted therefor.

The drive to achieve the strike of the knife can be brought about in any known manner. Just as it is conceivable to operate it manually, it can also be actuated by means of compressed air, a hydraulic system, or a solenoid through the actuating of a corresponding release switch.

A particularly simple and compact type of construction is obtained if the cutting strike is pneumatically actuated in accordance with the preferred embodiment. In accordance with the invention in this case it is possible to design the knife carrier in its upper portion as a cylinder whose outer jacket is provided with an external gear for the drive of its angular setting movement and whose internal wall co-operates with a stationary carrier bushing arranged coaxially to the presser-foot bar to form a compressed-air operated slide system. As a result of a corresponding subdivision of the internal wall of the knife carrier designed as a cylinder and the bearing bushing co-operating with this cylinder, there is achieved a particularly advantageous design of the knife carrier as a compressed-air actuated slide having a ring-shaped effective piston surface.

With regard to further advantageous embodiments of the preferred pneumatically actuated type of construction, reference is had to the explanation below of an exemplified embodiment and to the claims.

The invention is explained in detail with reference to the, annexed drawing of a preferred exemplified embodiment.

SUMMARY OF THE INVENTION A cutting device for cutting sewn tapes, laces and the like and adaptable for use on a sewing machine includes a knife means arranged behind a presser foot with respect to the direction of feed of the material being sewn. The knife means cooperates with a stationary anvil and is operable to effect a cutting and striking motion of the knife means substantially perpendicular to the surface of the material being sewn. Drive means are provided for actuating the knife means to effectuate the cutting and striking motion of the knife means. The knife means is rotatable about a bearing means which has an axis substantially perpendicular to the surface of the material being sewn, and adjustable means are provided for adjusting the angular position of the knife means about the axis of the bearing means.

BRIEF DESCRIPTION OF THE DRAWING The drawing schematically shows in an elevational view and partially in cross-section, a head of a sewing machine provided with a cutting device according to one embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the direction of feed of the sewing machine is designated by the reference numeral 29. A knife 5 arranged with respect to the direction of feed behind a needle bar 8 guiding a needle 9 and behind a presser foot 26 extends in the representation of the drawing with its blade perpendicular to the plane of the drawing and perpendicular to the direction of feed 29. The blade of the knife 5 co-operates with an anvil 7 which is arranged inside or on a guide plate 27 and whose material is softer than the material of the cutting blade. The strike or cutting motion of the knife is performed counter to the biasing effect of a return spring 28 arranged perpendicular to the guide plate 27, that is, preferably by means of a pneumatic knife driving device which is supplied or fed by the line 25. The arrangement described thus far does not however, constitute the object or main feature of the invention.

It is the object of the invention to create the possibility of imparting to the knife 5 not only a movement in the direction of the strike or cutting motion of the knife but, in addition, to render the blade of the knife pivotable around an axis 6 of its strike motion in any desired angular position with respect to the direction of feed 29. In order to obtain this angular setting of the blade there is provided an actuating lever 13 which can be pivoted around the axis 6 at a substantially equidistant spacing from the guide plate 27.

In accordance with the invention, all individual components required for the cutting device are carried by a bearing shaft 11 arranged in the sewing machine head 10 substantially perpendicular to the guide plate 27 as close as possible to the presser-foot bar. In the exemplified embodiment illustrated in the drawing, the bearing shaft 11 is constituted by the presser-foot bar itself, which, even though it is not of compelling necessity from the functional viewpoint, nevertheless affords the great advantage of reduced space requirement and the subsequent installment possibilities in existing sewing machines. If one uses the presser-foot bar as a bearing shaft for the cutting device, it is as a rule adequate to remove on a standard sewing machine the bushing constituting the presser foot bar bearing and to adapt the bottom wall of the sewing machine head for accommodating the cutting device through the arranging of corresponding recesses.

In accordance with the invention, a carrier sleeve 17 is arranged on the bearing shaft 11 whose upper end is sealed off with respect to the housing of the machine head 10 and whose central portion 18 is provided with a large outside diameter whereas its lower portion 19 is provided with a small outside diameter. As a result of this differential design of the outside diameters, the carrier sleeve 17 is subdivided into three sections of different diameter size. The central portion of the carrier sleeve 18 is provided with a longitudinal borehole 24a extending parallel to the bearing shaft 11 and cooperating with a duct 24b of the sewing machine head 10 as an air supply means.

The knife carrier generally referred to by the numeral 1 consists, in accordance with the invention, of an upper part 2 and a lower part 3. The knife carrier upper part 2 is designed as a hollow cylinder and is provided at the outer surface of its jacket with an external gear 4. At its internal surface, the upper part of the knife carrier 2 is designed with varying or different diameters so that the wall 20 at the upper end of the upper part 2 of the knife carrier corresponds to the outside diameter of the central portion 18 of the carrier sleeve whereas, in the lower area of the upper part 2 of the knife carrier, a segment-like lip 21 is fitted or provided on the outside diameter of the lower portion 19 of the carrier sleeve. Between the wall 20 of the upper part of the knife carrier 2 and the carrier sleeve 17 on the one hand, as well as between the lip 21 of the upper portion 2 of the knife carrier and the carrier sleeve 17, on the other, there are arranged seals 22 and 23, respectively.

The type of construction described above makes it possible to' have the knife carrier I perform with respect to the carrier sleeve 17, which is mounted in stationary condition in the sewing machine, a rotary movement around the axis 6 as well as a longitudinal movement in the direction of the axis 6. Air pressure built up via the pressure line 25 exerts downward pressure on the knife carrier 1 in any angular relative position of the knife carrier 1, with the air pressure on the knife carrier being effective on an annular surface whose diameters substantially correspond to the inside diameters of the wall 20 and the lip 21 of the upper portion 2 of the knife carrier.

The outside gear 4 of the upper part 2 of the knife carrier mates in accordance with the invention with an internal gear 15 of an actuating pawl 16 forming the shorter leg of the U-shaped lever 13 for the setting of the oblique position of U-shaped lever 13. The longer leg of U-shaped lever 13 carries a bearing 14 which is pivotally carried on the bearing shaft 11.

It can be seen that, on the one hand, an angular displacement of the setting lever 13 with respect to the bearing shaft 11 results in a corresponding displacement of the upper portion 2 of the knife carrier and thereby in a change of the position of the blade of the knife 5 with respect to the direction of feed 29, and that, on the other, the strike or cutting motion of the knife is possible independently of the respective relative angular position between the knife 5 and the direction of feed 29.

In accordance with the invention, the cutting knife 5 is provided with a stirrup-like shape with the two links extending vertically to the blade serving for the attaching of the knife 5 to the lower part 3 of the knife carrier by means of two screws 12. The lower part 3 of the knife carrier is undercut with respect of the upper part 2 of the knife carrier preferably up to the elevation of the axis of the cutting knife movement so that the blade of the cutting knife 5 extends diametrically to such axis.

The device in accordance with the invention permits the sewing machine operator manually to adjust from case to case the angle of the cut to be performed as required to any desired size and to actuate the knife strike, following setting of the oblique position. However, it is of course also possible to automatically adjust the oblique position setting lever by means of a work scanning device with respect to the shape of the edge of the work, in which arrangement, by means of a corresponding blocking circuit, the actuation of the knife strike must be rendered dependent on the completed setting of the oblique position.

Within the framework of the invention it is not absolutely essential that the knife strike be actuated pneumatically or hydraulically. One may also consider an electromagnetic actuation of the knife strike. In this case, it could be appropriate to swing the solenoid directly around the bearing shaft and to secure the relative position of the knife carrier with respect to the solenoid by means of a groove guide.

I claim:

1. A cutting device for cutting sewn tapes, laces, and the like and adapted for use on a sewing machine of the type having a presser foot and a stationary anvil, comprising a knife means arranged behind said presser foot with respect to the direction of feed of the material being sewn, said knife means cooperating with said stationary anvil and being operable to provide a striking and cutting motion of said knife means substantially perpendicular to the surface of the material being sewn, drive means for actuating said knife means to effectuate said striking and cutting motion of said knife means, bearing means about which said knife means is rotatable, said bearing means having an axis substantially perpendicular to the surface of the material being sewn, adjustable means for adjusting the angular position of said knife means about said axis, said presser foot having a support bar, said axis of said bearing means being disposed parallel to said support bar, said axis of said bearing means and support bar being generally aligned in the direction of feed of said sewn material, said knife means including a knife carrier having an upper portion arranged as a cylinder, said adjustable means including external gear means on said cylinder providing for rotation of said cylinder, said cylinder being formed with a hollow portion and having means defining an internal wall, a stationary carrier sleeve disposed in said hollow portion of said cylinder, said cylinder being slidable relative to said stationary carrier sleeve, said cylinder and stationary carrier sleeve defining a pneumatically operable power means for effecting said striking and cutting motion of said knife means, and biasing means providing a biasing force in a direc tion opposite to the direction in which said knife means is moved during said cutting and striking operation, said stationary carrier sleeve being disposed with its longitudinal axis arranged generally coaxial with said presser foot support bar.

2. A cutting device as set forth in claim 1 wherein said cylinder has a lower portion having means defining a segment-like lip, said carrier sleeve having a lower portion cooperating with said segment-like lip, said lower portion of said carrier sleeve having an outer diameter smaller than the outer diameter of an upper portion thereof, said upper portion of said carrier sleeve having a passage disposed parallel to the axis of said carrier sleeve, duct means arranged in the sewing machine and in communication with a source of compressed air, said passage being in communication with said duct means.

'3. A cutting device as set forth in claim 2 including seal means disposed between the upper portion of said carrier sleeve and said internal wall of said cylinder, and seal means disposed at said lower portion of said carrier sleeve and adjacent to said segment-like lip.

4. A cutting device as set forth in claim 1 wherein said knife means includes a cutting blade and two links extending perpendicular to said cutting blade, said two links defining means for attaching said knife blade to said knife carrier.

5. A cutting device as set forth in claim 1 wherein said knife carrier has an upper portion extending laterally beyond an undercut part of a lower portion of said knife carrier, said knife blade being mounted on said knife carrier such that said knife blade is arranged diametrically relative to the axis of said cylinder.

6. A cutting device as set forth in claim 1, said adjustable means further including an actuating lever pivotal about said bearing means, said actuating lever including an actuating pawl, an internal gear mounted on said actuating pawl and operable to engage said external gear on said cylinder of said knife means, whereby pivotal movement of said actuating lever adjusts the angular position of said knife means.

7. A cutting device as set forth in claim 6 wherein said internal gear mounted on said actuating lever is pivotal about an axis which is coaxial with said presser foot support bar. 

1. A cutting device for cutting sewn tapes, laces, and the like and adapted for use on a sewing machine of the type having a presser foot and a stationary anvil, comprising a knife means arranged behind said presser foot with respect to the direction of feed of the material being sewn, said knife means cooperating with said stationary anvil and being operable to provide a striking and cutting motion of said knife means substantially perpendicular to the surface of the material being sewn, drive means for actuating said knife means to effectuate said striking and cutting motion of said knife means, bearing means about which said knife means is rotatable, said bearing means having an axis substantially perpendicular to the surface of the material being sewn, adjustable means for adjusting the angular position of said knife means about said axis, said presser foot having a support bar, said axis of said bearing means being disposed parallel to said support bar, said axis of said bearing means and support bar being generally aligned in the direction of feed of said sewn material, said knife means including a knife carrier having an upper portion arranged as a cylinder, said adjustable means including external gear means on said cylinder providing for rotation of said cylinder, said cylinder being formed with a hollow portion and having means defining an internal wall, a stationary carrier sleeve disposed in said hollow portion of said cylinder, said cylinder being slidable relative to said stationary carrier sleeve, said cylinder and stationary carrier sleeve defining a pneumatically operable power means for effecting said striking and cutting motion of said knife means, and biasing means providing a biasing force in a direction opposite to the direction in which said knife means is moved during said cutting and striking operation, said stationary carrier sleeve being disposed with its longitudinal axis arranged generally coaxial with said presser foot support bar.
 2. A cutting device as set forth in claim 1 wherein said cylinder has a lower portion having means defining a segment-like lip, said carrier sleeve having a lower portion cooperating with said segment-like lip, said lower portion of said carrier sleeve having an outer diameter smaller than the outer diameter of an upper portion thereof, said upper portion of said carrier sleeve having a passage disposed parallel to the axis of said carrier sleeve, duct means arranged in the sewing machine and in communication with a source of compressed air, said passage being in communication with said duct means.
 3. A cutting device as set forth in claim 2 including seal means disposed between the upper portion of said carrier sleeve and said internal wall of said cylinder, and seal means disposed at said lower portion of said carrier sleeve and adjacent to said segment-like lip.
 4. A cutting device as set forth in claim 1 wherein said knife means includes a cutting blade and two links extending perpendicular to said cutting blade, said two links defining means for attaching said knife blade to said knife carrier.
 5. A cutting device as set forth in claim 1 wherein said knife carrier has an upper portion extending laterally beyond an undercut part of a lower portion of said knife carrier, said knife blade being mounted on said knife carrier such That said knife blade is arranged diametrically relative to the axis of said cylinder.
 6. A cutting device as set forth in claim 1, said adjustable means further including an actuating lever pivotal about said bearing means, said actuating lever including an actuating pawl, an internal gear mounted on said actuating pawl and operable to engage said external gear on said cylinder of said knife means, whereby pivotal movement of said actuating lever adjusts the angular position of said knife means.
 7. A cutting device as set forth in claim 6 wherein said internal gear mounted on said actuating lever is pivotal about an axis which is coaxial with said presser foot support bar. 